The subject matter disclosed herein relates generally to post-object collimators for detectors (e.g., collimators positioned at detectors that detect x-rays after passing through a patient), and more particularly, to collimators for imaging detectors, such as Computed Topography (CT) scanners.
Multislice image scanners, such as multislice CT scanners, having increased speed and larger coverage areas can provide higher resolution diagnostic images. For example, images with greater anatomic detail or diagnostically relevant information may be provided. For example, different details of interest in diagnosis may be small structures, features, and objects associated with normal anatomy and various pathological conditions. However, one of the limiting factors in the visualization of these small structures and features can be the artifacts introduced by the imaging system. In particular, one such known limiting factor in medical imaging systems that may introduce image artifacts during image reconstruction is focal spot drift, which is also known as focal spot motion.
The focal spot motion may be caused by different factors, such as movement of the gantry system relative to the object being scanned, imaging system calibration errors, air calibration errors, misalignment of the anode or degrading x-ray tube glass, oscillation of the focal spot clue to mechanical vibration, thermal changes, among others. Thus, reducing the focal spot motion results in a reduction in artifacts in reconstructed images,
Some conventional imaging system use skewed detector collimators to desensitize the detector to focal spot motion. By skewing the collimator, collimation on each side of a pixel is provided. However, this skewed collimation reduces the light collection because the x-ray aperture is reduced. The skew reduces the geometric efficiency of the detector, but decreases the collimator sensitivity to geometric tolerances and the focal spot motion.